The present invention generally relates to sealing joints in construction machines. The present invention particularly relates to a track link assembly having a resiliently bonded protectively coated seal member and an associated method for maintaining a track link assembly.
Construction machines, such as crawler tractors, typically include a sprocket, an idler, a track link assembly, and a number of track shoes attached to the track link assembly to form a track group. The aforementioned components cooperate to propel the crawler tractor over the ground.
Track link assemblies generally include a number of bushings and entrained track links. The bushings and track links cooperate to form a number of track joints. Track joints are typically equipped with a track seal assembly to keep out various corrosive and abrasive mixtures of water, dirt, sand, rock or other mineral or chemical elements to which the track link assembly is exposed during its use. The presence of these corrosive and abrasive mixtures in the track joint can damage the track link assembly. The track seal assembly also functions to keep a lubricant within the track joint which facilitates the operation of the track link assembly.
One existing track seal assembly design used in an attempt to accomplish the aforementioned functions employs a sealing member axially urged into sliding sealing engagement against a polished bushing end face by a resilient rubber load ring. However, a number of problems have been encountered using this seal design over long periods of time.
One such problem relates to grooving of the bushing end face. The mixtures of various abrasive particles found in the working environment of the track link assembly tend to make excellent grinding compounds which can wear grooves into the bushing end face. If these grooves become sufficiently deep, the integrity of the track seal assembly can be compromised and abrasive particles can enter the track joint. These grooves also provide a path for the lubricant contained within the track joint to leak out.
The aforementioned problems can cause track joint failure. Therefore, the end faces are periodically inspected to determine the extent of grooving therein. If the grooving is significant the entire bushing is typically replaced which increases the cost of maintaining the crawler tractor.
Another existing track seal assembly design used in an attempt to accomplish the aforementioned functions utilizes an annular wear resistant plate bonded with an adhesive either directly to the end face of the bushing or to an intermediary elastomeric annular plate. While this seal assembly design reduces the problem of grooving in the end face, it introduces another serious problem, that being the failure of the adhesive bond between the bushing end face and the annular wear resistant plate. The failure of the adhesive bond also results in the loss of sealing and subsequent track joint failure.
The present invention is directed to overcoming one or more of the problems set forth above.